Traveling internationally by air is not as easy as it used to be. Threats of terrorism have prompted tighter security regulations, identity thieves have forced the Transportation Safety Administration to require fraud-proof personal IDs and customs officials have stepped up inspections of goods imported into the U.S. While traveling abroad incurs more security checks than flying domestically, preparing your documents and luggage in advance will streamline your experience at U.S. airports.

Passports

Since 2007, the State Department has required all legal U.S. residents traveling to any foreign country to have a valid passport. This essential document includes proof of name, date of birth, nationality, and a standard photo for international identification. Newer passports contain a microchip with scannable information as well. Department of Homeland Security personnel will stamp the pages of the passport booklet when you leave and re-enter the U.S., so don’t leave home without it.

Security Checkpoint

Security screenings are strictly enforced in all U.S. airports, and international travelers might receive an extra dose of scrutiny. Regardless of foreign destination, all passengers go through a metal detector and, at some airports, a full-body scanner. Your luggage will pass through an X-ray machine to detect banned objects, such as weapons or hazardous substances. TSA regulations also prohibit any liquids, gels or aerosols over three ounces in your carry-on luggage -- these products must fit inside a quart-size plastic bag and be screened separately from the rest of your baggage.

Customs Declaration

When you return to the U.S. from abroad, you will complete a customs declaration form before leaving your plane and entering the customs area at the airport. Usually, a flight attendant will distribute the forms to passengers just before landing at your destination. The U.S. imposes taxes, known as duties, on some items purchased abroad, such as alcohol and tobacco products. You must declare these items on your customs form or risk paying a fine.

Agricultural Products

The U.S. Department of Agriculture bans passengers from bringing some plants, animals and animal products into the U.S. from abroad. The measures are meant to protect native species and livestock from diseases and invasive pests. If you acquire any fruits, vegetables, meats or other food products from overseas, it’s a good idea to declare them on your customs form. The USDA also prohibits importation of soil, live animals, shells, sand and biological materials without a permit. If you plan to import these items, obtain the right permit before your trip.